Braking control device

Abstract

A braking control device, includes a regenerative braking control part, a wheel speed differential detection part, and a regenerative restriction part. The regenerative braking control part is configured to carrying out regenerative braking on the drive wheels based on a deceleration request operation. The wheel speed differential detection part is configured to determine a wheel speed differential between the driven wheel speed and the regenerative braking wheel speed. The regenerative restriction part is configured to restrict the regenerative braking amount when the wheel speed differential exceeds a restriction initiation threshold value. The regenerative restriction part, during restriction of the regenerative braking amount, is configured to repeatedly carrying out a restriction in accordance with a large restriction phase in which a decrease in gradient of the regenerative braking amount is large and a restriction in accordance with a small restriction phase in which the decrease in gradient is small.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a U.S. National stage application of International Application No. PCT / JP2013 / 055716, filed Mar. 1, 2013, which claims priority to Japanese Patent Application No. 2012-049936 filed in Japan on Mar. 7, 2012, the contents of each of which are hereby incorporated herein by reference.BACKGROUND[0002]1. Field of the Invention[0003]The present invention relates to a braking control device in which a regenerative braking control part carries out regenerative braking only on the front or back drive wheels in a vehicle such as an electric or hybrid car.[0004]2. Background Information[0005]In the past, electrically actuated boost devices have been known in which assisted thrust is provided by an electrically powered actuator to an assist member in accordance with movement of an input member by the brake driver, generating hydraulic brake pressure that has been boosted in a master cylinder (e.g., refer to Japanese Laid-Open Paten...

AI Technical Summary

Benefits of technology

[0011]The present invention focuses on the problems described above, and an aim of the invention is to provide a braking control device whereby it is possible to decrease changes in vehicle behavior and reduce uncomfortable sensations in the driver during restriction of the regenerative braking amount when carrying out regenerative braking control of the driven wheels which are at the front or rear.

[0014]For this reason, in accordance with restriction in the large restriction phase, the braking amount at the regenerative braking wheels is equal to or less than the torque corresponding to the coefficient of friction at the road surface, inhibiting changes in vehicle behavior. In addition, in accordance with restriction in the small restriction phase, fluctuation in vehicle deceleration due to frictional response lag is suppressed, which suppresses uncomfortable sensations in the driver.

Problems solved by technology

However, as stated above, in systems in which the braking pressure of the four wheels is controlled at the same pressure, because either the front or rear wheels are used as drive wheels, when regenerative coordinated control is carried out at the braking wheels, the following problems may arise.

Specifically, when regenerative coordinated control is carried out, the regenerative braking amount is restricted in cases where the wheel speed differential relative to the driven wheels increases due to the action of regenerative braking force and the friction braking force at the drive wheels.

When this occurs, there are cases in which the regenerative braking restriction amount is insufficient, and the braking force on the drive wheels in such cases becomes greater than the corresponding coefficient of friction of the road surface, resulting in understeering or oversteering which can have a detrimental influence on vehicle behavior.

On the other hand, if the regenerative braking restriction amount is increased in order to induce a decrease in driven wheel braking force, the amount of fluctuation in vehicle deceleration will increase due to the response lag of the friction braking force, which may induce and uncomfortable sensation in the driver.

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